This invention relates, in general, to forming conductors in flexible membranes, and more specifically to producing elastomeric materials containing patterns of fine line conductors.
Producing fine geometry electrically conducting materials, conductors with features on the order of 50 microns or less, on elastomeric materials has been difficult to achieve. The elastomer's flexible characteristic required the material to be supported in some manner for forming any type of conductor pattern either in or on the elastomer. Even when supported, the flexible property made it difficult to maintain a motionless state for the formation of small feature conductors. Additionally, elastomers could not withstand the high temperatures associated with applying conductors by evaporating or sputtering methods, therefore, the conductor materials that could be applied were limited. For those materials that could be applied reliably, silk screening or shadow mask manufacturing techniques were generally employed.
Silk screening of conductors usually employed applying conductive inks through a screen mask held in contact with the elastomer to be coated. Conducting inks that could be applied with silk screening were generally limited to metal particles suspended in a liquid or paste that could flow through the screen onto the elastomer.
Shadow masks were generally more rigid than silk screens and could support smaller geometry in the mask openings. Smaller openings facilitated improved control, but, the resulting feature size on the elastomeric material was limited not only by mask openings but also by the movement of the elastomer itself. As with silk screening, the elastomeric material's flexible characteristic required that it be supported while in contact with the shadow mask. Supporting the elastomer could not provide enough rigidity to sufficiently control the tolerances of the applied pattern for fine line conductors.
These flexible and heat sensitive properties have restricted previous manufacturing methods in producing elastomeric materials having fine geometry conductors.
Accordingly it would be desirable to have a method for producing accurately placed, fine line conductors in elastomeric materials.